/*
 * This file is part of Apparat.
 *
 * Apparat is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Apparat is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Apparat. If not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright (C) 2009 Joa Ebert
 * http://www.joa-ebert.com/
 *
 */

package apparat.graph

class DepthFirstTraversal[V](graph: GraphLike[V], startVertex: V)
		extends GraphTraversal[V] with ListBasedTraversal[V] {
	protected lazy val vertexList = {
		var list: List[V] = Nil
		var visited = graph vertexMap (v => false)
		var S = List(startVertex)

		while (S.nonEmpty) {
			val v = S.head
			S = S.tail
			if (!visited(v)) {
				list = v :: list
				visited = visited updated (v, true)
				S = graph.successorsOf(v).filterNot(visited(_)).toList ::: S
			}
		}

		list
	}
}